VCSEL as sensing element to measure distance changes in the nm-range

Abstract

We investigated a novel sensor concept based on a coupled resonator configuration and the employment of verticalcavity surface-emitting laser (VCSEL) sources. Hereby, the back reflection of a sample which is placed next to the emission window of the semiconductor based laser source affects the internal resonator conditions of the VCSEL. If the operating voltage is kept constant, the internal interaction results in a change of the emitted wavelength and operating current, respectively. First experiments show a reproducible change of the operating current when the sample is moved in vertical direction by a few nm. This behavior was previously verified with a simulation based on ANSYS Lumerical by creating distributed Bragg reflection (DBR) stacks with different layers and quantifying the influence of the movable third resonator surface on the emission wavelength.